Steering columns have diverse functions in motor vehicles. They firstly serve for fastening the steering wheel and for mounting the steering shaft or steering spindle on the vehicle body. They also serve for fastening add-on parts, such as, for example, an anti-theft means or operator control elements. The steering columns are sometimes also adjustable mechanically or electrically in the axial direction and vertical direction in order to be able to adapt the position of the steering wheel to the requirements of the driver. Finally, steering columns are also intended to yield in a controlled manner in the event of an impact of the vehicle against an obstacle, in order to absorb impact energy of the driver against the steering wheel and thereby to reduce the risk of injury for the driver. Along with all of these requirements, it is also required that steering columns take up little construction space, have a low weight and operate without play and noise.
In addition, steering columns are intended to be as reasonably priced as possible.
The document EP 1 550 598 A1 presents a steering column in which the rigidity of the casing unit is increased by targeted enlargement or expansion of the cross section of the casing tube manufactured from sheet metal. The mounting of the steering spindle is designed here as a rolling bearing at its lower end which lies at the front in the direction of travel and therefore faces away from the steering column. The bearing seat of the rolling bearing is formed in a spacer or adaptor which is manufactured from resin or a rubber-elastic material and is intended to absorb vibrations.
The fastening of the adaptor to the lower end of the casing unit constitutes a restriction which may lead to undesirable effects. Furthermore, such adaptors are affected by tolerances, in particular in this combination of materials, and therefore have an influence on the rigidity and natural frequency of the steering column in an unforeseeable manner. However, in particular in the event of a crash, good support of the steering spindle has to be ensured in order to prevent uncontrolled movements which could harm the driver.